1. Field of the Invention
The present invention relates to an image forming method.
2. Description of the Related Art
Printed images represented by photographic images, posters, and so on, have recently been able to be fabricated by an ink jet device, and an image forming apparatus using an electro-photographic method due to development of digital processing technologies, in addition to a conventional silver halide photographic process, and a printing method such as gravure printing. Some printed matters such as photographic images and posters fabricated by such an image forming apparatus require typography in which a gloss surface is uniformly formed on the entire surface of a recording material.
From this background, techniques have been studied for forming a uniform gloss surface in the electro-photographic method. Specifically, an image forming apparatus has appeared which fabricates a printed matter in which a high gloss surface is uniformly formed by a device called a gloss imparting device. This device is connected to an electro-photographic printer or the like, and heats and presses a toner layer formed by the printer from a color toner and a clear toner, while the toner layer is in contact with a belt member. Then, the surface of the toner layer is cooled while being in contact with the belt member so as to solidify the toner layer, and finally, the printed matter is peeled off from the belt member. Thus, an image having a uniform high gloss surface is provided (for example, see Japanese Patent Application Laid-open Publication No. 2002-341619). This is called a cooling-and-peeling method, in which a heated toner layer is cooled while being closely adhered to a belt member, and then peeled off in a solidified state, thus transferring a shape of the belt member to the toner layer. Thus, a printed matter having a uniform high gloss surface is obtained.
There is also known a method in which such a high gloss image is formed on both sides. For example, Japanese Patent Application Laid-open Publication No. 2010-39238 discloses that a double-sided image is formed by performing gloss processing at a plurality of stages on both front and back sides of a recording material.
In a method described in Japanese Patent Application Laid-open Publication No. 2010-39238, similar gloss processing is used for both front and back sides. However, there has been a problem in that, when a uniform high gloss image is formed in this method on one side of an image recording medium such as paper, and another image is formed on the back side thereof using this method, a gloss level of the high gloss image which is formed first is decreased, and an image having a desired gloss level is not able to be obtained.
In order to solve this problem, a method has been proposed to have the same gloss level on both sides by changing fixing conditions for the front side and back side, as disclosed in, for example, Japanese Patent Application Laid-open Publication No. 2009-14823.
However, the gloss processing method disclosed in Japanese Patent Application Laid-open Publication No. 2009-14823 above, the same toner is used for the front side and the back side, and the fixing conditions are changed. Therefore, there has been a problem in that a device becomes complicated and it takes time to output images. Hence, improvement is required.
Meanwhile, when a clear toner which is appropriate for gloss processing, in other words, a clear toner which has a low elasticity and is thus easily deformed by heat, is used for a front side and a back side, thermal blocking tends to happen as gloss-processed images on both sides are stacked on each other.